U.S. patent application number 14/665281 was filed with the patent office on 2015-10-01 for image reader and computer-readable medium for the same.
This patent application is currently assigned to BROTHER KOGYO KABUSHIKI KAISHA. The applicant listed for this patent is BROTHER KOGYO KABUSHIKI KAISHA. Invention is credited to Yoshikazu KAWAUCHI.
Application Number | 20150281488 14/665281 |
Document ID | / |
Family ID | 54192132 |
Filed Date | 2015-10-01 |
United States Patent
Application |
20150281488 |
Kind Code |
A1 |
KAWAUCHI; Yoshikazu |
October 1, 2015 |
Image Reader and Computer-Readable Medium for the Same
Abstract
An image reader including a conveyor, a first detector, a
plurality of second detectors, a reading unit, and a controller
configured to perform a control process that includes determining
whether second detection information output from the second
detectors satisfies a predetermined state, executing a first
sequence when determining that the second detection information
satisfies the predetermined state, the first sequence including
determining whether a conveyed object is in a multi-feed condition
based on first detection information output from the first
detector, and halting at least one of a conveying operation by the
conveyor and a reading operation by the reading unit when
determining that the conveyed object is in the multi-feed
condition, executing a second sequence when determining that the
second detection information does not satisfy the predetermined
state, the second sequence including continuing the conveying
operation and the reading operation regardless of the first
detection information.
Inventors: |
KAWAUCHI; Yoshikazu;
(Nagoya, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BROTHER KOGYO KABUSHIKI KAISHA |
Nagoya-shi |
|
JP |
|
|
Assignee: |
BROTHER KOGYO KABUSHIKI
KAISHA
Nagoya-shi
JP
|
Family ID: |
54192132 |
Appl. No.: |
14/665281 |
Filed: |
March 23, 2015 |
Current U.S.
Class: |
358/1.13 |
Current CPC
Class: |
H04N 1/0057
20130101 |
International
Class: |
H04N 1/00 20060101
H04N001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2014 |
JP |
2014-071271 |
Claims
1. An image reader comprising: a conveyor configured to perform a
conveying operation of conveying a conveyed object in a conveyance
direction, the conveying object being one of a document sheet and a
carrier sheet with a document sheet held therein; a first detector
configured to output first detection information representing
whether the conveyed object is in a multi-feed condition in which
the conveyed object overlaps another conveyed object; a plurality
of second detectors spaced apart from each other in a direction
intersecting the conveyance direction, each second detector being
configured to output second detection information representing
whether there is an object being conveyed; a reading unit disposed
downstream relative to the first detector and the plurality of
second detectors in the conveyance direction, the reading unit
being configured to perform a reading operation of reading an image
of the conveyed object; and a controller configured to perform a
control process of controlling the conveying operation by the
conveyor and the reading operation by the reading unit, the control
process comprising: determining whether the second detection
information output from the plurality of second detectors satisfies
a predetermined state; executing a first sequence when determining
that the second detection information output from the plurality of
second detectors satisfies the predetermined state, the first
sequence comprising: determining whether the conveyed object is in
the multi-feed condition, based on the first detection information
output from the first detector; and halting at least one of the
conveying operation and the reading operation, when determining
that the conveyed object is in the multi-feed condition; executing
a second sequence when determining that the second detection
information output from the plurality of second detectors does not
satisfies the predetermined state, the second sequence comprising:
continuing the conveying operation by the conveyor and the reading
operation by the reading unit, regardless of the first detection
information output from the first detector.
2. The image reader according to claim 1, further comprising two
side guides configured to guide the conveyed object in the
conveyance direction, at least one of the two side guides being
movable in a direction perpendicular to the conveyance direction,
wherein the plurality of second detectors comprise at least two
second detectors disposed in a conveyance area defined between the
two side guides in the conveyance direction when the two side
guides are positioned closest to each other.
3. The image reader according to claim 1, wherein the first
sequence further comprises: when determining that the conveyed
object is not in the multi-feed condition, continuing the conveying
operation and the reading operation; during a period in which the
controller continues the conveying operation and the reading
operation, determining whether the conveyed object is in the
multi-feed condition based on the first detection information
output from the first detector, until a point of time when the
controller determines that there is not an object being conveyed
based on the second detection information output from the plurality
of second detectors; and in response to determining that the
conveyed object is in the multi-feed condition, halting at least
one of the conveying operation and the reading operation,
regardless of whether the second detection information output from
the plurality of second detectors satisfies the predetermined
state.
4. The image reader according to claim 3, wherein the controller is
configured to resume the control process of controlling the
conveying operation and the reading operation when determining that
there is an object being currently conveyed based on the second
detection information output from at least one of the plurality of
second detectors, after determining that there is not an object
being currently conveyed based on the second detection information
output from the plurality of second detectors.
5. The image reader according to claim 1, wherein each of the
plurality of second detectors comprises: a rotatable element
disposed to be rotatable around an axis perpendicular to the
conveyance direction; and an optical sensor configured to detect
rotation of the rotatable element.
6. The image reader according to claim 5, wherein the conveyor is
configured to convey the carrier sheet with a bonded portion
thereof directed downstream in the conveyance direction, the bonded
portion of the carrier sheet being formed by bonding end portions
of two transparent sheets together, the carrier sheet having a
cutout formed at the bonded portion, wherein one of the plurality
of second detectors is disposed to detect the cutout formed at the
bonded portion of the carrier sheet in response to the rotatable
element of the one second detector coming into contact with the
cutout and rotates, and wherein another one of the plurality of
second detectors is disposed to detect a non-cutout part of the
bonded portion where the cutout is not formed, in response to the
rotatable element of the another second detector coming into
contact with the non-cutout part and rotates.
7. The image reader according to claim 6, wherein the controller is
configured to determine that the second detection information
output from the plurality of second detectors does not satisfy the
predetermined state, when the second detection information output
from the plurality of second detectors includes a point of time
when the rotatable element of the one second detector has come into
contact with the cutout and a point of time when the rotatable
element of the another second detector has come into contact with
the non-cutout part.
8. The image reader according to claim 1, wherein the first
detector comprises an ultrasonic sensor.
9. An image reader comprising: a conveyance roller configured to
rotate to convey a medium to be read, along a conveyance direction;
an ultrasonic sensor; a first sensor and a second sensor spaced
apart from each other in a direction intersecting the conveyance
direction; a reading unit disposed downstream relative to the
ultrasonic sensor, the first sensor, and the second sensor in the
conveyance direction; and a controller configured to: determine
whether a time difference between a first timing and a second
timing satisfies a predetermined relationship, the first timing
being a point of time when the controller receives detection
information from the first sensor, the second timing being a point
of lime when the controller receives detection information from the
second sensor; execute a first sequence in response to determining
that the time difference between the first timing and the second
timing satisfies the predetermined relationship, the first sequence
comprising: determining whether multi-feed is occurring based on
detection information from the ultrasonic sensor; and stopping at
least one of rotation of the conveyance roller and light emission
from the reading unit in response to determining that the
multi-feed is occurring; and execute a second sequence in response
to determining that the time difference between the first timing
and the second timing does not satisfy the predetermined
relationship, the second sequence comprising: continuing the
rotation of the conveyance roller and the light emission from the
reading unit regardless the detection information from the
ultrasonic sensor.
10. The image reader according to claim 9, wherein the controller
is configured to determine that the time difference between the
first timing and the second timing satisfies the predetermined
relationship when the first timing is coincident with the second
timing.
11. A non-transitory computer-readable medium storing
computer-readable instructions that are executable by a processor
coupled with an image reader comprising: a conveyance roller
configured to rotate to convey a medium to be read, along a
conveyance direction; an ultrasonic sensor; a first sensor and a
second sensor spaced apart from each other in a direction
intersecting the conveyance direction; and a reading unit disposed
downstream relative to the ultrasonic sensor, the first sensor, and
the second sensor in the conveyance direction, the instructions
being configured to, when executed by the processor, cause the
processor to: determine whether a time difference between a first
timing and a second timing satisfies a predetermined relationship,
the first timing being a point of time when the processor receives
detection information from the first sensor, the second timing
being a point of time when the processor receives detection
information from the second sensor; execute a first sequence in
response to determining that the time difference between the first
timing and the second timing satisfies the predetermined
relationship, the first sequence comprising: determining whether
multi-feed is occurring based on detection information from the
ultrasonic sensor; and stopping at least one of rotation of the
conveyance roller and light emission from the reading unit in
response to determining that the multi-feed is occurring; and
execute a second sequence in response to determining that the time
difference between the first timing and the second timing does not
satisfy the predetermined relationship, the second sequence
comprising: continuing the rotation of the conveyance roller and
the light emission from the reading unit regardless the detection
information from the ultrasonic sensor.
12. The non-transitory computer-readable medium according to claim
11, wherein the instructions are configured to, when executed by
the processor, cause the processor to determine that the time
difference between the first timing and the second timing satisfies
the predetermined relationship when the first timing is coincident
with the second timing.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 U.S.C. .sctn.119
from Japanese Patent Application No. 2014-071271 filed on Mar. 31,
2014. The entire subject matter of the application is incorporated
herein by reference.
BACKGROUND
[0002] 1. Technical Field
[0003] The following description relates to one or more aspects of
an image reading apparatus and a computer-readable medium
therefor.
[0004] 2. Related Art
[0005] An image reader has been known that is provided with a
separation conveyance operational mode and a non-separation
conveyance operational mode. In the separation conveyance
operational mode, when the image reader determines that multi-feed
occurs, based on detection information output from a multi-feed
detector, the image reader halts conveyance of sheets or
continuously conveys the sheets to a sheet discharge unit.
Meanwhile, in the non-separation conveyance operational mode, when
the multi-feed detector detects a half-folded document sheet, the
image reader reads the detected half-folded document sheet. The
operational mode is switched between the separation conveyance
operational mode and the non-separation conveyance operational
mode, through an operation of a changeover switch or an operation
of a personal computer (hereinafter referred to as a "PC" in an
abbreviation form).
SUMMARY
[0006] According to aspects of the present disclosure, an image
reader is provided that includes a conveyor configured to perform a
conveying operation of conveying a conveyed object in a conveyance
direction, the conveyed object being one of a document sheet and a
carrier sheet with a document sheet held therein, a first detector
configured to output first detection information representing
whether the conveyed object is in a multi-feed condition in which
the conveyed object overlaps another conveyed object, a plurality
of second detectors spaced apart from each other in a direction
intersecting the conveyance direction, each second detector being
configured to output second detection information representing
whether there is an object being conveyed, a reading unit disposed
downstream relative to the first detector and the plurality of
second detectors in the conveyance direction, the reading unit
being configured to perform a reading operation of reading an image
of the conveyed object, and a controller configured to perform a
control process of controlling the conveying operation by the
conveyor and the reading operation by the reading unit, the control
process including determining whether the second detection
information output from the plurality of second detectors satisfies
a predetermined state, executing a first sequence when determining
that the second detection information output from the plurality of
second detectors satisfies the predetermined state, the first
sequence including determining whether the conveyed object is in
the multi-feed condition, based on the first detection information
output from the first detector, and halting at least one of the
conveying operation and the reading operation, when determining
that the conveyed object is in the multi-feed condition, executing
a second sequence when determining that the second detection
information output from the plurality of second detectors does not
satisfy the predetermined state, the second sequence including
continuing the conveying operation by the conveyor and the reading
operation by the reading unit, regardless of the first detection
information output from the first detector.
[0007] According to aspects of the present disclosure, further
provided is an image reader including a conveyance roller
configured to rotate to convey a medium to be read, along a
conveyance direction, an ultrasonic sensor, a first sensor and a
second sensor spaced apart from each other in a direction
intersecting the conveyance direction, a reading unit disposed
downstream relative to the ultrasonic sensor, the first sensor, and
the second sensor in the conveyance direction, and a controller
configured to determine whether a time difference between a first
timing and a second timing satisfies a predetermined relationship,
the first timing being a point of time when the controller receives
detection information from the first sensor, the second timing
being a point of time when the controller receives detection
information from the second sensor, execute a first sequence in
response to determining that the time difference between the first
timing and the second timing satisfies the predetermined
relationship, the first sequence including determining whether
multi-feed is occurring based on detection information from the
ultrasonic sensor, and stopping at least one of rotation of the
conveyance roller and light emission from the reading unit in
response to determining that the multi-feed is occurring, and
execute a second sequence in response to determining that the time
difference between the first timing and the second timing does not
satisfy the predetermined relationship, the second sequence
including continuing the rotation of the conveyance roller and the
light emission from the reading unit regardless the detection
information from the ultrasonic sensor.
[0008] According to aspects of the present disclosure, further
provided is a non-transitory computer-readable medium storing
computer-readable instructions that are executable by a processor
coupled with an image reader including a conveyance roller
configured to rotate to convey a medium to be read, along a
conveyance direction, an ultrasonic sensor, a first sensor and a
second sensor spaced apart from each other in a direction
intersecting the conveyance direction, and a reading unit disposed
downstream relative to the ultrasonic sensor, the first sensor, and
the second sensor in the conveyance direction, the instructions
being configured to, when executed by the processor, cause the
processor to determine whether a time difference between a first
timing and a second timing satisfies a predetermined relationship,
the first timing being a point of time when the processor receives
detection information from the first sensor, the second timing
being a point of time when the processor receives detection
information from the second sensor, execute a first sequence in
response to determining that the time difference between the first
timing and the second timing satisfies the predetermined
relationship, the first sequence including determining whether
multi-feed is occurring based on detection information from the
ultrasonic sensor, and stopping at least one of rotation of the
conveyance roller and light emission from the reading unit in
response to determining that the multi-feed is occurring, and
execute a second sequence in response to determining that the time
difference between the first timing and the second timing does not
satisfy the predetermined relationship, the second sequence
including continuing the rotation of the conveyance roller and the
light emission from the reading unit regardless the detection
information from the ultrasonic sensor.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0009] FIG. 1 is a perspective view showing an image reader when an
upper portion of a main body thereof is open, in accordance with
one or more aspects of the present disclosure.
[0010] FIG. 2 is a cross-sectional side view showing the image
reader in accordance with one or more aspects of the present
disclosure.
[0011] FIG. 3 is a plane view showing the image reader in
accordance with one or more aspects of the present disclosure.
[0012] FIG. 4 is a plane view showing a positional relationship
between a document detector (document detecting sensors) and a
carrier sheet in a left-to-right direction, in accordance with one
or more aspects of the present disclosure.
[0013] FIG. 5 is a block diagram showing an electrical
configuration of the image reader in accordance with one or more
aspects of the present disclosure.
[0014] FIGS. 6A and 6B are flowcharts showing a procedure of a
process to be executed by a central processing unit (hereinafter,
which may be referred to as a "CPU") of the image reader in
accordance with one or more aspects of the present disclosure.
[0015] FIG. 7 is a timing chart showing variations of output values
from the document detector (the document detecting sensors) and a
multi-feed detector when document sheets are successfully separated
and conveyed, in accordance with one or more aspects of the present
disclosure.
[0016] FIG. 8 is a timing chart showing variations of output values
from the document detector (the document detecting sensors) and the
multi-feed detector when a carrier sheet is conveyed, in accordance
with one or more aspects of the present disclosure.
[0017] FIG. 9 is a timing chart showing variations of output values
from the document detector (the document detecting sensors) and the
multi-feed detector when multi-feed occurs, in accordance with one
or more aspects of the present disclosure.
[0018] FIG. 10 is a timing chart showing variations of output
values from the document detector (the document detecting sensors)
and the multi-feed detector when drawing multi-feed occurs, in
accordance with one or more aspects of the present disclosure.
DETAILED DESCRIPTION
[0019] It is noted that various connections are set forth between
elements in the following description. It is noted that these
connections in general and, unless specified otherwise, may be
direct or indirect and that this specification is not intended to
be limiting in this respect. Aspects of the present disclosure may
be implemented on circuits (such as application specific integrated
circuits) or in computer software as programs storable on
computer-readable media including but not limited to RAMs, ROMs,
flash memories, EEPROMs, CD-media, DVD-media, temporary storage,
hard disk drives, floppy drives, permanent storage, and the
like.
[0020] Generally, in reading an easily-damageable sheet or an
abnormally-shaped sheet, the easily-damageable sheet or the
abnormally-shaped sheet is conveyed and read by the image reader in
a state where the easily-damageable sheet or the abnormally-shaped
sheet is held in a carrier sheet. The carrier sheet is formed with
a plurality of transparent sheets mutually overlapping. When a
document sheet sandwiched between the transparent sheets of the
carrier sheet is read in the separation conveyance operational
mode, the document sheet and the plurality of transparent sheets
are conveyed together in an overlapped manner. Therefore, at this
time, the image reader might determine that the sheets are conveyed
in a multi-feed manner. When determining that the sheets are
conveyed in a multi-feed manner, the image reader halts conveyance
of the sheets or continuously conveys the sheets to the sheet
discharge unit without reading the sheets.
[0021] To prevent the image reader from mistakenly identifying a
situation where the carrier sheet is being conveyed as occurrence
of multi-feed, a user is required to perform a troublesome
operation of, e.g., operating the changeover switch of the image
reader or operating the PC connected with the image reader to
switch between the separation conveyance operational mode and the
non-separation conveyance operational mode.
[0022] Aspects of the present disclosure are advantageous to
provide one or more improved techniques, for an image processing
apparatus, which do not need user's troublesome operations for
switching the operational mode.
[0023] Hereinafter, an illustrative embodiment according to aspects
of the present disclosure will be described with reference to the
accompanying drawings. In the following description, a
front-to-rear direction, a left-to-right direction, and a vertical
direction of an image reader 1 of the illustrative embodiment will
be defined as shown in FIGS. 1 to 4.
[0024] (Mechanical Configuration of Image Reader)
[0025] FIG. 1 is a perspective view showing the image reader 1 when
an upper portion 4 of a main body 2 of the image reader 1 is open.
The image reader 1 includes the main body 2 and a document tray 3.
The main body 2 includes the upper portion 4 and a lower portion 5.
The upper portion 4 is attached to the lower portion 5. The upper
portion 4 is openable and closable relative to the lower portion 5.
The document tray 3 is disposed behind the main body 2. Switches 6
and light-emitting diodes 7 (hereinafter referred to as "LEDs 7")
are disposed at the upper portion 4 of the main body 2. The
switches 6 are configured to accept user operations. The LEDs 7 are
configured to indicate operational states of the image reader
1.
[0026] FIG. 2 is a cross-sectional side view for illustrating a
configuration of the image reader 1. A conveyance path 30, along
which document sheets are conveyed, is defined between the upper
portion 4 and the lower portion 5 of the main body 2. The
conveyance path 30 is slanted downward in a direction forward from
the document tray 3. In other words, as shown in FIG. 2, the
conveyance path 30 is defined between a downward-facing surface of
the upper portion 4 and an upward-facing surface of the lower
portion 5, when the upper portion 4 is closed relative to the lower
portion 5. The document sheets are conveyed forward from the
document tray 3 along the conveyance path 30. In FIG. 2, the
conveyance path 30 is indicated by an alternate long and two short
dashes arrow. An orientation of the arrow exemplifies a conveyance
direction. The conveyance direction corresponds to a direction in
which the document sheets are conveyed, i.e., a direction from the
document tray 3 toward the discharge rollers 17 along the
conveyance path 30. Namely, as shown in FIG. 2, the conveyance
direction is a direction from an upper rear portion to a lower
front portion of the image reader 1. Along the conveyance path 30,
there are disposed two side guides 10, a front sensor 18, a pickup
roller 11, a document separator 12, a multi-feed detector 13, feed
rollers 14, a document detector 15, a reading unit 16, and
discharge rollers 17. Further, a controller 20 of the image reader
1 is disposed at the lower portion 5 of the main body 2.
[0027] As shown in FIG. 3, the two side guides 10 are attached to
the document tray 3 to be movable in the left-to-right direction
along grooves formed on the document tray 3. The two side guides 10
are positioned the same distance away, in respective different
directions along the left-to-right direction, from a middle point
of a length of the document tray 3 in the left-to-right direction.
Each side guide 10 has a rack (not shown) extending in the
left-to-right direction, inside the document tray 3. Inside the
document tray 3, a pinion gear (not shown) is provided. Engagement
between the pinion gear and the rack of each side guide 10 enables
the two side guides 10 to move symmetrically in the left-to-right
direction with respect to the middle point of the length of the
document tray 3 in the left-to-right direction. When the two side
guides 10 are moved in respective different directions along the
left-to-right direction, document sheets placed between the two
side guides 10 are restricted from moving in the left-to-right
direction and guided onto the conveyance path 30 by the two side
guides 10. The pickup roller 11 is disposed downstream relative to
the document tray 3 in the conveyance direction. The document
sheets placed between the two side guides 10, on the document tray
3, are conveyed along the conveyance path 30 by rotation of the
pickup roller 11. As shown in FIG. 2, the document separator 12 is
a plate-shaped member. The document separator 12 is disposed at the
upper portion 4. The document separator 12 faces the pickup roller
11 across the conveyance path 30. Namely, the document separator 12
is a separation pad. The document separator 12 is pressed against
the pickup roller 11. The document sheets are pressed by the
document separator 12 and separated on a sheet-by-sheet basis by a
friction force acting between the sheets and the document separator
12.
[0028] The multi-feed detector 13 is disposed downstream relative
to the document separator 12 in the conveyance direction. In the
illustrative embodiment, the multi-feed detector 13 includes an
ultrasonic sensor that includes a receiver 13A and a transmitter
13B. The receiver 13A is disposed at the lower portion 5. The
transmitter 13B is disposed at the upper portion 4. The transmitter
13B faces the receiver 13A across the conveyance path 30.
Alternatively, the receiver 13A may be disposed at the upper
portion 4, and the transmitter 13B may be disposed at the lower
portion 5. The feed rollers 14 are disposed downstream relative to
the multi-feed detector 13 in the conveyance direction. The feed
rollers 14 are configured to feed the document sheets further
downstream in the conveyance direction.
[0029] As shown in FIG. 3, the document detector 15 includes two
document detecting sensors 15L and 15R. In the illustrative
embodiment, the document detecting sensors 15L and 15R are disposed
at the upper portion 4 of the main body 2 and downstream relative
to the feed rollers 14 in the conveyance direction. Hereinafter,
the document detecting sensors 15L and 15R may collectively be
referred to as the document detector 15, when the sensors 15L and
15R need not be discriminated from each other. In the illustrative
embodiment, each of the document detecting sensors 15L and 15R
includes a rotatable element 15A and a photo-coupler 15B. The
rotatable element 15A is disposed to be rotatable in a direction
along the conveyance direction. Namely, the rotatable element 15A
is configured to rotate around an axis 15C extending in the
left-to-right direction. Since the axis 15C is parallel to the
left-to-right direction, it is understood that the rotatable
element 15A, when rotating clockwise or counterclockwise, rotates
parallel to the conveyance direction. An end portion of the
rotatable element 15A protrudes from the upper portion 4 to the
conveyance path 30, so as to contact document sheets. When the end
portion of the rotatable element 15A comes into contact with a
document sheet, the other end portion of the rotatable element 15A
comes away from a position to block an optical path of the
photo-coupler 15B, such that the rotatable element 15A does not
block the optical path of the photo-coupler 15B. A detailed
explanation will be provided later about disposition and operations
of the document detector 15, with reference to FIGS. 3 and 4.
[0030] As shown in FIG. 2, the front sensor 18 is disposed at the
upper portion 4 of the main body 2 and upstream relative to the
pickup roller 11 in the conveyance direction. In the illustrative
embodiment, the front sensor 18 includes a movable element and a
photo-coupler. The movable element is disposed to be rotatable in a
direction along the conveyance direction. An end portion of the
movable element protrudes from the upper portion 4 to the
conveyance path 30, so as to contact the document sheets placed on
the document tray 3. When the end portion of the movable element
comes into contact with a document sheet, the other end portion of
the movable element comes away from a position to block an optical
path of the photo-coupler, such that the movable element does not
block the optical path of the photo-coupler.
[0031] The reading unit 16 is disposed downstream relative to the
document detector 15 in the conveyance direction. The reading unit
16 includes contact image sensors (hereinafter referred to as
"CISs" in an abbreviated form) configured to read images of
document sheets being conveyed. In the illustrative embodiment, a
main scanning direction and a sub scanning direction of the CISs
are the left-to-right direction and the conveyance direction,
respectively. The discharge rollers 17 are disposed at the lower
portion 5 of the main body 2 and downstream relative to the reading
unit 16 in the conveyance direction. The discharge rollers 17 are
configured to convey the document sheets of which the images have
been read by the reading unit 16, outside from the image reader
1.
[0032] FIG. 3 is a plane view of the lower portion 5 of the main
body 2 of the image reader 1 in the illustrative embodiment. The
upper portion 4 of the main body 2 is not shown in FIG. 3. Although
the document detecting sensors 15L and 15R are disposed at the
upper portion 4, FIG. 3 does not show the document detecting sensor
15L or 15R but indicates disposition areas 31L and 31R of the
document detecting sensors 15L and 15R by alternate long and two
short dashes lines, for the sake of explanatory convenience. In
FIG. 3, movable areas 32 of the side guides 10 are indicated by
alternate long and two short dashes arrows. Further, in FIG. 3, a
shortest distance 33 between the two side guides 10 when the two
side guides 10 are positioned closest to each other is shown by an
alternate long and two short dashes line. Moreover, in FIG. 3, a
left end 34L and a right end 34R of a conveyance area defined by
the two side guides 10 positioned closest to each other are shown
by alternate long and short dashes lines.
[0033] Between the left end 34L and the right end 34R of the
conveyance area defined by the two side guides 10 when the two side
guides 10 are positioned closest to each other, the two document
detecting sensors 15L and 15R are arranged along the left-to-right
direction perpendicular to the conveyance direction. Further, the
two document detecting sensors 15L and 15R are positioned the same
distance away, in respective different directions along the
left-to-right direction, from the middle point of the length of the
document tray 3 in the left-to-right direction.
[0034] Referring to FIG. 4, an explanation will be provided about a
relative positional relationship between the document detector 15
and a carrier sheet 40. The carrier sheet 40 is formed by bonding
end portions of two transparent sheets together. The carrier sheet
40 is conveyed with an easily-damageable document sheet or an
abnormally-shaped document sheet sandwiched between the two
transparent sheets of the carrier sheet 40. A bonded portion of the
two transparent sheets is a leading end portion 40A. At the leading
end portion 40A, a cutout 41 is formed. The cutout 41 may be
formed, e.g., with a length of 10 mm in the conveyance direction of
the carrier sheet 40 and a length of 10 mm in the left-to-right
direction of the carrier sheet 40. The carrier sheet 40 is conveyed
with the leading end portion 40A thereof directed downward in the
conveyance direction. When a document sheet held in the carrier
sheet 40 (i.e., a document sheet sandwiched between the transparent
sheets of the carrier sheet 40) is read, the positions of the two
side guides 10 are adjusted by a user, according to the size of the
carrier sheet 40. The carrier sheet 40 is placed between the two
side guides 10 of which the positions have been adjusted. When the
user operates one of the switches 6, the carrier sheet 40 begins to
be conveyed. The rotatable element 15A of the document detecting
sensor 15R comes into contact with a non-cutout part, where the
cutout 41 is not formed, of the leading end portion 40A of the
carrier sheet 40. Meanwhile, the rotatable element 15A of the
document detecting sensor 15L comes into contact with an edge
portion of the cutout 41 formed at the leading end portion 40A of
the carrier sheet 40. A detection moment when the document
detecting sensor 15L comes into contact with the edge portion of
the cutout 41 is later than a detection moment when the document
detecting sensor 15R comes into contact with the non-cutout part of
the leading end portion 40A. For example, at such a conveyance
speed as to enable conveyance of 50 A4-sized sheets per minute, an
absolute time difference may be equal to or more than 0.02 seconds
between the detection moment when the document detecting sensor 15L
comes into contact with the edge portion of the cutout 41 and the
detection moment when the document detecting sensor 15R comes into
contact with the non-cutout part of the leading end portion 40A.
When a document sheet is conveyed without the carrier sheet 40, a
detection moment when the rotatable element 15A of the document
detecting sensor 15L comes into contact with the document sheet is
the same as a detection moment when the rotatable element 15A of
the document detecting sensor 15R comes into contact with the
document sheet. For example, the same detection moment means that,
at such a conveyance speed as to enable conveyance of 50 A4-sized
sheets per minute, an absolute time difference may be equal to or
less than 0.01 seconds between the detection moment when the
document detecting sensor 15L detects the document sheet and the
detection moment when the document detecting sensor 15R detects the
document sheet. A threshold for determining whether the two
detection moments are the same may be changed as needed depending
on the conveyance speed. For example, at such a conveyance speed as
to enable conveyance of 25 A4-sized sheets per minute, the absolute
time difference may be equal to or less than 0.02 seconds between
the two detection moments.
[0035] (Electrical Configuration of Image Reader)
[0036] FIG. 5 is a block diagram schematically showing an
electrical configuration of the image reader 1. The image reader 1
includes the controller 20 configured to take control of operations
of conveying and reading document sheets. The controller 20
includes a central processing unit 21 (hereinafter referred to as a
"CPU 21"), a read-only memory 22 (hereinafter referred to as a "ROM
22"), and a random access memory 23 (hereinafter referred to as a
"RAM 23"). The controller 20 is connected with the switches 6, the
LEDs 7, a driving unit 53, a reading unit 16, an analog front end
50 (hereinafter referred to as an "AFE 50"), the multi-feed
detector 13, the document detector 15, and the front sensor 18.
[0037] The ROM 22 is configured to store various computer programs
such as programs for controlling operations of the image reader 1
and a program for executing a process shown in FIGS. 6A and 6B. The
ROM 22 is an example of non-transitory storage media. Instead of
the ROM 22, another one (such as a flash ROM) of the non-transitory
storage media may be used. It is noted that the non-transitory
storage media axe configured to store information therein, and do
not include transitory media such as transmission signals. The CPU
21 is configured to control the image reader 1 in accordance with
the programs, stored in the ROM 22, for controlling operations of
the image reader 1. The RAM 23 is configured to temporarily store
information received from elements included in the image reader
1.
[0038] Each of the switches 6 is configured to accept a user
operation and transmit information corresponding to the accepted
operation to the CPU 21. When receiving information from the
switches 6, the image reader 1 performs the process shown in FIGS.
6A and 6B.
[0039] The LEDs 7 are configured to show states of the image reader
1. For example, the LEDs 7 may include two LEDs. One of the LEDs
may be configured to be turned on in green when the image reader 1
is in a stand-by state. The other LED may be configured to be
turned on in red when an error such as multi-feed occurs.
[0040] The driving unit 53 includes a motor (not shown) for driving
the pickup roller 11, the feed rollers 14, and the discharge
rollers 17. When the motor is driven or stopped according to an
instruction from the CPU 21, the pickup roller 11, the feed rollers
14, and the discharge rollers 17 are rotated or stopped.
[0041] The reading unit 16 includes a light source 51 and a light
receiver 52. The light source 51 includes LEDs of the three primary
colors (RGB). The reading unit 16 turns on each of the LEDs of RGB
in accordance with a turn-on instruction from the CPU 21. In
addition, the reading unit 16 turns off each of the LEDs of RGB in
accordance with a turn-off instruction from the CPU 21. The light
receiver 52 is configured to receive light reflected by a document
sheet being conveyed along the conveyance path 30 and generate an
analog signal corresponding to a quantity of the received light.
The light receiver 52 transmits, to the AFE 50, an analog signal
corresponding to a light receiving quantity of reflected light that
is originally derived from light emitted by each of the three
LEDs.
[0042] The AFE 50 includes an amplifier, a filter, and an A/D
convertor. The AFE 50 is connected with the reading unit 16 and the
controller 20. The AFE 50 converts an analog signal received from
the light receiver 52 of the reading unit 16 into a digital signal.
Read data as the digital signal acquired through the A/D conversion
is transmitted to the controller 20. A plurality of pieces of read
data are combined by the CPU 21 and stored into the RAM 23 as image
data of a single image.
[0043] When one or more document sheets traverse a position between
the receiver 13A and the transmitter 13B of the multi-feed detector
13, an amplitude of an ultrasonic wave transmitted by the
transmitter 13B is attenuated, and the receiver 13A receives the
ultrasonic wave with the attenuated amplitude. An attenuation
amount of the ultrasonic wave depends on the number of the document
sheets positioned between the receiver 13A and the transmitter 13B.
Specifically, the larger the number of the document sheets is, the
larger the attenuation amount of the ultrasonic wave is. Meanwhile,
the smaller the number of the document sheets is, the smaller the
attenuation amount of the ultrasonic wave is. The multi-feed
detector 13 transmits, to the CPU 21, amplitude information showing
the attenuated amplitude as detected. The CPU 21 determines the
attenuation amount by calculation based on the amplitude
information on the attenuated amplitude that has been received from
the receiver 13A and reference amplitude information acquired when
there was no document sheet being conveyed. For instance, the
calculation may be to obtain a difference between the amplitude
information and the reference amplitude information or a ratio of
the amplitude information to the reference amplitude information.
Determination as to whether multi-feed has occurred is made based
on whether the calculated attenuation amount is more than a
threshold indicating occurrence of multi-feed. The reference
amplitude information acquired when there was no document sheet
being conveyed and the threshold indicating occurrence of
multi-feed are previously stored in the ROM 22.
[0044] The document detector 15 is configured to detect whether
there is a document sheet being conveyed. When the end portion of
the rotatable element 15A rotates after contacting a document sheet
being conveyed, the other end portion of the rotatable element 15A
continuously contacts the document sheet and does not block the
optical path of the photo-coupler 15B. Each of the document
detecting sensors 15L and 15R of the document detector 15 transmits
detection information to the CPU 21.
[0045] The front sensor 18 is configured to detect whether there is
a document sheet placed on the document tray 3. When the end
portion of the movable element of the front sensor 18 rotates after
contacting a document sheet placed on the document tray 3, the
other end portion of the movable element does not block the optical
path of the photo-coupler of the front sensor 18. The photo-coupler
detects whether the movable element blocks the optical path of the
photo-coupler, and transmits detection information to the CPU 21.
For instance, when detecting that the movable element does not
block the optical path of the photo-coupler, the photo-coupler may
transmit ON information as the detection information to the CPU 21.
Meanwhile, when detecting that the movable element blocks the
optical path of the photo-coupler, the photo-coupler may transmit
Off information as the detection information to the CPU 21. The
movable element is in contact with a document sheet until all
document sheets are fed out of the document tray 3. The
photo-coupler detects that the movable element does not block the
optical path of the photo-coupler, and transmits the ON information
as the detection information to the CPU 21.
[0046] (Control by CPU)
[0047] FIGS. 6A and 6B are flowcharts showing a procedure of a
process to be executed by the CPU 21 of the image reader 1. When
accepting an instruction to start image reading through the
switches 6, the CPU 21 starts the process shown in the flowchart of
FIGS. 6A and 6B in accordance with the program stored in the ROM
22.
[0048] In S100, the CPU 21 transmits, to the driving unit 53, a
conveyance starting instruction to start a conveying operation.
Thereafter, the CPU 21 goes to S101.
[0049] In S101, the CPU 21 determines whether at least one of the
document detecting sensors 15L and 15R has detected a document
sheet. When determining that at least one of the document detecting
sensors 15L and 15R has detected a document sheet (i.e., when
determining that the detection information received from at least
one of the document detecting sensors 15L and 15R is ON
information) (S101: Yes), the CPU 21 goes to S102. Meanwhile, when
determining that the detection information received from each of
the document detecting sensors 15L and 15R is OFF information)
(S101: No), the CPU 21 repeats the operation of S101. In the
following description, a particular point of time when the
detection information is changed from the OFF information to the ON
information will be referred to as the "document-leading-end
detection timing." Further, a particular point of time when the
detection information is changed from the ON information to the OFF
information will be referred to as a "document-trailing-end
detection timing."
[0050] In S102, the CPU 21 determines whether the detection
information received from the document detecting sensors 15L and
15R satisfies a first state. When not satisfying the first state,
the detection information received from the document detecting
sensors 15L and 15R satisfies a second state. It is noted that when
a document sheet is being conveyed, the detection information
received from the document detecting sensors 15L and 15R satisfies
the first state. Meanwhile, when a carrier sheet 40 is being
conveyed, the detection information received from the document
detecting sensors 15L and 15R satisfies the second state.
Specifically, in S102, the CPU 21 compares a document-leading-end
detection timing identified based on the detection information
received from the document detecting sensor 15L with a
document-leading-end detection timing identified based on the
detection information received from the document detecting sensor
15R. Namely, the CPU 21 determines whether a time difference
between a particular point of time when the CPU 21 has received the
detection information from the document detecting sensor 15L and a
particular point of time when the CPU 21 has received the detection
information from the document detecting sensor 15R satisfies a
predetermined relationship. When determining that the two
document-leading-end detection timings are coincident with each
other, the CPU 21 determines that the detection information
received from the document detecting sensors 15L and 15R satisfies
the first state. In this case, the CPU 21 makes an affirmative
determination in S102 (S102: Yes), and executes, as a first
sequence, S110 and subsequent operations. Further, in this case,
the CPU 21 determines that the aforementioned time difference
satisfies the predetermined relationship. Meanwhile, when
determining that the two document-leading-end detection timings are
different, the CPU 21 determines that the detection information
received from the document detecting sensors 15L and 15R does not
satisfy the first state (but satisfies the second state). In this
case, the CPU 21 makes a negative determination in S102 (S102: No),
and executes S120 as a second sequence. Further, in this case, the
CPU 21 determines that the aforementioned time difference does not
satisfy the predetermined relationship.
[0051] In S110, the CPU 21 determines whether the attenuation
amount based on the amplitude information received from the
multi-feed detector 13 is more than the threshold indicating
occurrence of multi-feed that is previously stored in the ROM 22.
When determining that the attenuation amount based on the amplitude
information received from the multi-feed detector 13 is more than
the threshold indicating occurrence of multi-feed (S110: Yes), the
CPU 21 goes to S130. Meanwhile, when determining that the
attenuation amount based on the amplitude information received from
the multi-feed detector 13 is not more than the threshold
indicating occurrence of multi-feed (S110: No), the CPU 21 goes to
S111.
[0052] In S111, the CPU 21 transmits to the reading unit 16 a
turn-on instruction to turn on the light source 51. To read the
document sheet in color, the CPU 21 transmits to the reading unit
16 a turn-on instruction to turn on the LEDs of the three primary
colors RGB in a time division manner. To read the document sheet in
monochrome, the CPU 21 transmits to the reading unit 16 a turn-on
instruction to turn on one or all of the LEDs of RGB. After S111,
the CPU 21 goes to S112.
[0053] In S112, the CPU 21 combines a plurality of pieces of read
data. Specifically, the light receiver 52 receives light reflected
by a part of the document sheet being conveyed along the conveyance
path 30, and transmits to the AFE 50 an analog signal corresponding
to a quantity of the received light. The AFE 50 converts the
received analog signal into a digital signal. The digital signal
acquired through the A/D conversion by the AFE 50 is a piece of
partial read data of the document sheet. Therefore, the CPU 21
combines a plurality of pieces of partial read data, and stores
into the RAM 23 the combined read data as image data of a single
whole image.
[0054] In S113, in die same manner as S110, the CPU 21 determines
whether the attenuation amount based on the amplitude information
received from the multi-feed detector 13 is more than the threshold
indicating occurrence of multi-feed that is previously stored in
the ROM 22. When determining that the attenuation amount based on
the amplitude information received from the multi-feed detector 13
is more than the threshold indicating occurrence of multi-feed
(S113: Yes), the CPU 21 goes to S140. Meanwhile, when determining
that the attenuation amount based on the amplitude information
received from the multi-feed detector 13 is not more than the
threshold indicating occurrence of multi-feed (S113: No), the CPU
21 goes to S114.
[0055] In S114, the CPU 21 determines whether the document
detecting sensors 15L and 15R have detected a document-trailing-end
detection timing, based on the detection information received from
the document detecting sensors 15L and 15R. When determining that
the document detecting sensors 15L and 15R have detected a
document-trailing-end detection timing (S114: Yes), the CPU 21 goes
to S115. Meanwhile, when determining that the document detecting
sensors 15L and 15R have not detected a document-trailing-end
detection timing (S114: No), the CPU 21 goes to S112. Namely, as
long as the CPU 21 determines in S113 that the attenuation amount
based on the amplitude information received from the multi-feed
detector 13 is not more than the threshold indicating occurrence of
multi-feed (S113: No), the CPU 21 continues a conveying operation
of conveying the document sheet and a reading operation of reading
the document sheet via execution of S112 and the negative
determination in S114 (S114: No).
[0056] In S115, the CPU 21 transmits to the reading unit 16 a
turn-off instruction to turn off the light source 51. Thereafter,
the CPU 21 goes to S116.
[0057] In S116, the CPU 21 transmits to the driving unit 53 a
conveyance halting instruction to halt the conveying operation.
Thereafter, the CPU 21 goes to S117.
[0058] In S117, the CPU 21 determines whether there is a document
sheet or a carrier sheet 40 placed on the document tray 3, based on
detection information received from the front sensor 18. When
determining that there is a document sheet or a carrier sheet 40
placed on the document tray 3 (S117: Yes), the CPU 21 goes to S100.
Meanwhile, when determining that there is not a document sheet or a
carrier sheet 40 placed on the document tray 3 (S117: No), the CPU
21 terminates the process shown in FIGS. 6A and 6B.
[0059] In S120, the CPU 21 transmits to the reading unit 16 a
turn-on instruction to turn on the light source 51. To read the
document sheet in color, the CPU 21 transmits to the reading unit
16 a turn-on instruction to turn on the LEDs of the three primary
colors RGB in a time division manner. To read the document sheet in
monochrome, the CPU 21 transmits to the reading unit 16 a turn-on
instruction to turn on one or all of the LEDs of RGB. After S120,
the CPU 21 goes to S121.
[0060] In S121, the CPU 21 combines a plurality of pieces of read
data. Specifically, the light receiver 52 receives light reflected
by a part of the document sheet being conveyed along the conveyance
path 30, and transmits to the AFE 50 an analog signal corresponding
to a quantity of the received light. The AFE 50 converts the
received analog signal into a digital signal. The digital signal
acquired through the A/D conversion by the AFE 50 is a piece of
partial read data of the document sheet. Therefore, the CPU 21
combines a plurality of pieces of partial read data, and stores
into the RAM 23 the combined read data as image data of a single
whole image.
[0061] In S122, in the same manner as S114, the CPU 21 determines
whether the document detecting sensors 15L and 15R have detected a
document-trailing-end detection timing, based on the detection
information received from the document detecting sensors 15L and
15R. When determining that the document detecting sensors 15L and
15R have detected a document-trailing-end detection timing (S122:
Yes), the CPU 21 goes to S123. Meanwhile, when determining that the
document detecting sensors 15L and 15R have not detected a
document-trailing-end detection timing (S122: No), the CPU 21 goes
to S121. Namely, when determining in S102 that the two
document-leading-end detection timings are different (S102: No),
the CPU 21 continues the conveying operation and the reading
operation via execution of S121 and the negative determination in
S122 (S122: No), regardless of the amplitude information received
from the multi-feed detector 13.
[0062] In S123, the CPU 21 transmits to the reading unit 16 a
turn-off instruction to turn off the light source 51. Thereafter,
the CPU 21 goes to S124.
[0063] In S124, the CPU 21 transmits to the driving unit 53 a
conveyance halting instruction to halt the conveying operation.
Thereafter, the CPU 21 goes to S125.
[0064] In S125, in the same manner as S117, the CPU 21 determines
whether there is a document sheet or a carrier sheet 40 placed on
the document tray 3, based on detection information received from
the front sensor 18. When determining that there is a document
sheet or a carrier sheet 40 placed on the document tray 3 (S125:
Yes), the CPU 21 goes to S100. Meanwhile, when determining that
there is not a document sheet or a carrier sheet 40 placed on the
tray 3 (S125: No), the CPU 21 terminates the process shown in FIGS.
6A and 6B.
[0065] In S130, the CPU 21 transmits to the driving unit 53 a
conveyance halting instruction to halt the conveying operation.
Further, the CPU 21 turns on an LED, which is for showing an error,
of the LEDs 7 in red. Thereafter, the CPU 21 terminates the process
shown in FIGS. 6A and 6B.
[0066] In S140, the CPU 21 transmits to the reading unit a turn-off
instruction to turn off the light source 51. Thereafter, the CPU 21
goes to S130.
Specific Operational Examples
[0067] In the image reader 1 of the illustrative embodiment, the
CPU 21 executes below-mentioned first to fourth operational
examples by automatically switching operations in accordance with
detection information and detection timings received from the
document detecting sensors 15L and 15R and detection information
received from the multi-feed detector 13, without a mode switching
operation by a user.
First Operational Example
Control of Document Reading when Multi-Feed is not Occurring
[0068] Referring to FIGS. 6A-6B and 7, an explanation will be
provided about control of a reading operation of reading document
sheets being conveyed without overlapping each other. In FIG. 7,
each of "t1" to "t8" represents a particular point of time when a
corresponding operation is executed or a corresponding event
occurs. Each of "t1" to "t8" will be referred to as an "operation
executing timing" or an "event occurrence timing."
[0069] The process shown in FIGS. 6A and 6B is launched in
accordance with information input through an operation of the
switches 6. At an operation executing timing t1, the CPU 21
transmits a conveyance starting instruction to the driving unit 53
(S100). In response to receipt of the conveyance starting
instruction, the driving unit 53 rotates the pickup roller 11, the
feed rollers 14, and the discharge rollers 17. Thereby, document
sheets placed on the document tray 3 are conveyed downstream in the
conveyance direction.
[0070] The document sheets are separated on a sheet-by-sheet basis
by the document separator 12. At an event occurrence timing t2, a
document sheet, which has passed through the document separator 12,
traverses the receiver 13A and the transmitter 13B of the
multi-feed detector 13. The event occurrence timing t2 is a
particular point of time when the amplitude information output from
the multi-feed detector 13 changes during a time period from the
operation executing timing t1 to a below-mentioned event occurrence
timing t3. Nevertheless, the CPU 21 continues the conveying
operation without determining whether the attenuation amount based
on the amplitude information is more than the threshold indicating
occurrence of multi-feed until the event occurrence timing t3. It
is noted that to "continue the conveying operation" means that the
CPU 21 does not transmit a conveyance halting instruction to the
driving unit 53 or that the CPU 21 transmits a conveyance
continuing instruction to the driving unit 53. Anyway, at the event
occurrence timing t2, the document conveyance has only to be
continued.
[0071] Subsequently, at the event occurrence timing t3, the
document detector 15 detects the document sheet (S101: Yes). The
CPU 21 compares the document-leading-end detection timing of the
document detecting sensor 15L with the document-leading-end
detection timing of the document detecting sensor 15R (S102). In
the first operational example, what is conveyed is a regular
document sheet that is not held in the carrier sheet 40. Therefore,
the CPU 21 determines that the document-leading-end detection
timing of the document detecting sensor 15L is coincident with the
document-leading-end detection timing of the document detecting
sensor 15R (S102: Yes). Thereafter, in response to the affirmative
determination in S102, the CPU 21 goes to S110.
[0072] In S110, the CPU 21 determines whether the attenuation
amount based on the amplitude information received from the
multi-feed detector 13 is more than the predetermined threshold. In
the first operational example, multi-feed is not occurring.
Therefore, the CPU 21 determines that the attenuation amount based
on the amplitude information received from the multi-feed detector
13 is not more than the predetermined threshold (S110: No).
Thereafter, the CPU 21 goes to S111.
[0073] At an operation executing timing t4, the CPU 21 transmits to
the reading unit 16 a turn-on instruction to turn on the light
source 51 (S111). In response to receipt of the turn-on
instruction, the reading unit 16 turns on the light source 51. To
read the document sheet in color, the reading unit 16 turns on the
LEDs of the three primary colors RGB in a time division manner. To
read the document sheet in monochrome, the reading unit 16 turns on
one or all of the LEDs of the three primary colors RGB.
[0074] The CPU executes S112, S113, and S114 during a time period
from the operation executing timing t4 to an event occurrence
timing t6. The light receiver 52 receives light reflected by the
document sheet, and transmits to the AFE 50 an analog signal
corresponding to a quantity of the received light. The AFE 50
performs A/D conversion of the received analog signal, and
transmits a digital signal acquired through the A/D conversion to
the CPU 21. Further, the CPU 21 combines a plurality of pieces of
read data, and stores into the RAM 23 the combined data as image
data of a single image (S112).
[0075] An event occurrence timing t5 is a particular point of time
when the amplitude information from the multi-feed detector 13 is
determined to have changed. At the event occurrence timing t5, the
CPU 21 determines whether the attenuation amount based on the
amplitude information received from the multi-feed detector 13 is
more than the threshold indicating occurrence of multi-feed that is
previously stored in the ROM 22 (S113). In the first operational
example, multi-feed is not occurring. Therefore, the CPU 21
determines that the attenuation amount based on the amplitude
information received from the multi-feed detector 13 is not more
than the predetermined threshold (S113: No). Thereafter, the CPU 21
goes to S114.
[0076] Next, the CPU 21 determines whether the document detecting
sensors 15L and 15R have detected a document-trailing-end detection
timing, based on the detection information received from the
document detecting sensors 15L and 15R (S114). At the event
occurrence timing t6, when determining that the document detecting
sensors 15L and 15R have detected a document-trailing-end detection
timing (S114: Yes), the CPU 21 goes to S115. Meanwhile, when
determining that the document detecting sensors 15L and 15R have
not detected a document-trailing-end detection timing (S114: No),
the CPU 21 goes to S112.
[0077] In S115, at an operation executing timing t7, the CPU 21
transmits to the reading unit 16 a turn-off instruction to turn off
the light source 51. In response to receipt of the turn-off
instruction, the reading unit 16 turns off the light source 51.
[0078] In S116, at an operation executing timing t8, the CPU 21
transmits a conveyance halting instruction to the driving unit 53.
In accordance with the conveyance halting instruction, the driving
unit 53 halts the rotations of the pickup roller 11, the feed
rollers 14, and the discharge rollers 17.
[0079] In S117, the CPU 21 determines whether there is a document
sheet or a carrier sheet 40 placed on the document tray 3, based on
the detection information received from the front sensor 18. When
determining that there is a document sheet or a carrier sheet 40
placed on the document tray 3 (S117: Yes), the CPU 21 goes to S100.
Meanwhile, when determining that there is not a document sheet or a
carrier sheet 40 placed on the document tray 3 (S117: No), the CPU
21 terminates the process shown in FIGS. 6A and 6B.
Second Operational Example
Control of Document Reading Using a Carrier Sheet
[0080] Referring FIGS. 6A-6B and 8, an explanation will be provided
about control of document reading using the carrier sheet 40. In
FIG. 8, each of "t11" to "t19" represents a particular point of
time when a corresponding operation is executed or a corresponding
event occurs. Each of "t11" to "t19" will be referred to as an
"operation executing timing" or an "event occurrence timing."
[0081] The process shown in FIGS. 6A and 6B is launched in
accordance with the information input through the operation of the
switches 6. At an operation executing timing t11, the CPU 21
transmits a conveyance starting instruction to the driving unit 53
(S100). In response to receipt of the conveyance starting
instruction, the driving unit 53 rotates the pickup roller 11, the
feed rollers 14, and the discharge rollers 17. Thereby, document
sheets placed on the document tray 3 are conveyed downstream in the
conveyance direction.
[0082] At an event occurrence timing t12, (a document sheet between
the transparent sheets of) the carrier sheet 40, which has passed
through the document separator 12, traverses the receiver 13A and
the transmitter 13B of the multi-feed detector 13. The event
occurrence timing t12 is a particular point of time when the
amplitude information output from the multi-feed detector 13
changes during a time period from the operation executing timing
t11 to a below-mentioned event occurrence timing t13. Nevertheless,
the CPU 21 continues the conveying operation without determining
whether the attenuation amount based on the amplitude information
is more than the threshold indicating occurrence of multi-feed
until the event occurrence timing t13. It is noted that to
"continue the conveying operation" means that the CPU 21 does not
transmit a conveyance halting instruction to the driving unit 53 or
that the CPU 21 transmits a conveyance continuing instruction to
the driving unit 53. Anyway, at the event occurrence timing t12,
the document conveyance has only to be continued. After passing
through the multi-feed detector 13, the document sheet (between the
transparent sheets of the carrier sheet 40) is further conveyed
downstream in the conveyance direction by the feed rollers 14.
[0083] Subsequently, at the event occurrence timing t13 (S101: Yes)
and an event occurrence timing 114, the document detecting sensors
15R and 15L detect the document sheet, respectively. The CPU 21
determines whether the document-leading-end detection timing of the
document detecting sensor 15L is coincident with the
document-leading-end detection timing of the document detecting
sensor 15R (S102). In the second operational example, the document
sheet is held in the carrier sheet 40. Further, the cutout 41 is
formed at the leading end portion 40A that is a bonded portion of
the transparent sheets of the carrier sheet 40. Therefore, the CPU
21 determines that the document-leading-end detection timing of the
document detecting sensor 15L is different from the
document-leading-end detection timing of the document detecting
sensor 15R, by a time delay caused due to the cutout 41 (S102: No).
Thereafter, the CPU 21 goes to S120.
[0084] At an operation executing timing t15, the CPU 21 transmits
to the reading unit 16 a turn-on instruction to turn on the light
source 51 (S120). In response to receipt of the turn-on
instruction, the reading unit 16 turns on the light source 51. To
read the document sheet in color, the reading unit 16 turns on the
LEDs of the three primary colors RGB in a time division manner. To
read the document sheet in monochrome, the reading unit 16 turns on
one or all of the LEDs of the three primary colors RGB.
[0085] The CPU executes S121 and S122 during a time period from the
operation executing timing t15 to an event occurrence timing t17.
The light receiver 52 receives light reflected by the document
sheet, and transmits to the AFE 50 an analog signal corresponding
to a quantity of the received light. The AFE 50 performs A/D
conversion of the received analog signal, and transmits a digital
signal acquired through the A/D conversion to the CPU 21. Further,
the CPU 21 combines a plurality of pieces of read data, and stores
into the RAM 23 the combined data as image data of a single image
(S112).
[0086] In the second operational example, each event occurrence
timing t16 is an example of a point of time when the amplitude
information changes. Nevertheless, the CPU 21 continues the
conveying operation without determining whether the attenuation
amount based on the amplitude information is more than the
threshold indicating occurrence of multi-feed. It is noted that to
"continue the conveying operation" means that the CPU 21 does not
transmit a conveyance halting instruction to the driving unit 53 or
that the CPU 21 transmits a conveyance continuing instruction to
the driving unit 53. Anyway, at the event occurrence timing t16,
the document conveyance has only to be continued. After passing
through the multi-feed detector 13, the document sheet (held in the
carrier sheet 40) is further conveyed downstream in the conveyance
direction by the feed rollers 14.
[0087] In S122, the CPU 21 determines whether the document
detecting sensors 15L and 15R have detected a document-trailing-end
detection timing, based on the detection information received from
the document detecting sensors 15L and 15R. When determining that
the document detecting sensors 15L, and 15R have detected a
document-trailing-end detection timing (S122: Yes), the CPU 21 goes
to S123. Meanwhile, when determining that the document detecting
sensors 15L and 15R have not detected a document-trailing-end
detection timing (S122: No), the CPU 21 goes to S121.
[0088] In S123, at an operation executing timing 118, the CPU 21
transmits to the reading unit 16 an turn-off instruction to turn
off the light source 51. In response to receipt of the turn-off
instruction, the reading unit 16 turns off the light source 51.
[0089] In S124, at an operation executing timing t19, the CPU 21
transmits a conveyance halting instruction to the driving unit 53.
In accordance with the conveyance halting instruction, the driving
unit 53 halts the rotations of the pickup roller 11, the feed
rollers 14, and the discharge rollers 17.
[0090] In S125, the CPU 21 determines whether there is a document
sheet or a carrier sheet 40 placed on the document tray 3, based on
the detection information received from the front sensor 18. When
determining that there is a document sheet or a carrier sheet 40
placed on the document tray 3 (S125: Yes), the CPU 21 goes to S100.
Meanwhile, when determining that there is not a document sheet or a
carrier sheet 40 placed on the document tray 3 (S125: No), the CPU
21 terminates the process shown in FIGS. 6A and 6B.
Third Operational Example
Control 1 of Document Reading when Multi-Feed is Occurring
[0091] Referring FIGS. 6A-6B and 9, an explanation will be provided
about control of document reading when multi-feed is occurring. In
FIG. 9, each of "t21" to "t24" represents a particular point of
time when a corresponding operation is executed or a corresponding
event occurs. Each of "t21" to "t24" will be referred to as an
"operation executing timing" or an "event occurrence timing."
[0092] The process shown in FIGS. 6A and 6B is launched in
accordance with the information input through the operation of the
switches 6. At an operation executing timing t21, the CPU 21
transmits a conveyance starting instruction to the driving unit 53
(S100). In response to receipt of the conveyance starting
instruction, the driving unit 53 rotates the pickup roller 11, the
feed rollers 14, and the discharge rollers 17. Thereby, document
sheets placed on the document tray 3 are conveyed downstream in the
conveyance direction.
[0093] At an event occurrence timing 122, a document sheet, which
has passed through the document separator 12, traverses the
receiver 13A and the transmitter 13B of the multi-feed detector 13.
The event occurrence timing t22 is a particular point of time when
the amplitude information output from the multi-feed detector 13
changes during a time period from the operation executing timing
t21 to an event occurrence timing t23. Nevertheless, the CPU 21
continues the conveying operation without determining whether the
attenuation amount based on the amplitude information is more than
the threshold indicating occurrence of multi-feed until the event
occurrence timing t23. It is noted that to "continue the conveying
operation" means that the CPU 21 does not transmit a conveyance
halting instruction to the driving unit 53 or that the CPU 21
transmits a conveyance continuing instruction to the driving unit
53. Anyway, at the event occurrence timing t22, the document
conveyance has only to be continued. After passing through the
multi-feed detector 13, the document sheet is further conveyed
downstream in the conveyance direction by the feed rollers 14.
[0094] Subsequently, at the event occurrence timing t23, the
document detector 15 detects the document sheet (S101: Yes). The
CPU 21 determines whether the document-leading-end detection timing
of the document detecting sensor 15L is coincident with the
document-leading-end detection timing of the document detecting
sensor 15R (S102). In the third operational example, what is
conveyed is a regular document sheet that is not held in the
carrier sheet 40. Therefore, the CPU 21 determines that the
document-leading-end detection timing of the document detecting
sensor 15L is coincident with the document-leading-end detection
timing of the document detecting sensor 15R, by a time delay
corresponding to the cutout 41 (S102: Yes). Thereafter, the CPU 21
goes to S110.
[0095] In S110, the CPU 21 determines whether the attenuation
amount based on the amplitude information received from the
multi-feed detector 13 is more than the predetermined threshold
indicating occurrence of multi-feed. In the third operational
example, multi-feed is occurring. Therefore, the CPU 21 determines
that the attenuation amount based on the amplitude information
received from the multi-feed detector 13 is more than the
predetermined threshold indicating occurrence of multi-feed (S110:
Yes). Thereafter, in response to the affirmative determination in
S110, the CPU 21 goes to S130.
[0096] In S130, at an operation executing timing t24, the CPU 21
transmits a conveyance halting instruction to the driving unit 53.
In accordance with the conveyance halting instruction, the driving
unit 53 halts the rotations of the pickup roller 11, the feed
rollers 14, and the discharge rollers 17. Further, the CPU 21 turns
on the TED, for showing an error, of the LEDs 7 in red. Thereafter,
the CPU 21 terminates the process shown in FIGS. 6A and 6B.
Fourth Operational Example
Control 2 of Document Reading when Multi-Feed is Occurring
[0097] Referring FIGS. 6A-6B and 10, an explanation will be
provided about control of document reading when drawing multi-feed
occurs in the middle of document conveyance. It is noted that
"drawing multi-feed" means a situation where a plurality of
document sheets, which have been once separated, are conveyed in an
overlapping manner with a document sheet being drawn by another
preceding document sheet. In FIG. 10, each of "t31" to "t37"
represents a particular point of time when a corresponding
operation is executed or a corresponding event occurs. Each of
"t31" to "t37" will be referred to as an "operation executing
timing" or an "event occurrence timing."
[0098] The process shown in FIGS. 6A and 6B is launched in
accordance with the information input through the operation of the
switches 6. At an operation executing timing t31, the CPU 21
transmits a conveyance starting instruction to the driving unit 53
(S100). In response to receipt of the conveyance starting
instruction, the driving unit 53 rotates the pickup roller 11, the
feed rollers 14, and the discharge rollers 17. Thereby, document
sheets placed on the document tray 3 are conveyed downstream in the
conveyance direction.
[0099] At an event occurrence timing t32, a document sheet, which
has passed through the document separator 12, traverses the
receiver 13A and the transmitter 13B of the multi-feed detector 13.
The event occurrence timing t32 is a particular point of time when
the amplitude information output from the multi-feed detector 13
changes during a time period from the operation executing timing
t31 to an event occurrence timing t33. Nevertheless, the CPU 21
continues the conveying operation without determining whether the
attenuation amount based on the amplitude information is more than
the threshold indicating occurrence of multi-feed until the event
occurrence timing t33. It is noted that to "continue the conveying
operation" means that the CPU 21 does not transmit a conveyance
halting instruction to the driving unit 53 or that the CPU 21
transmits a conveyance continuing instruction to the driving unit
53. Anyway, at the event occurrence timing t32, the document
conveyance has only to be continued. After passing through the
multi-feed detector 13, the document sheet is further conveyed
downstream in the conveyance direction by the feed rollers 14.
[0100] Subsequently, at the event occurrence timing t33, the
document detector 15 detects the document sheet (S101: Yes). The
CPU 21 determines whether the document-leading-end detection timing
of the document detecting sensor 15L is coincident with the
document-leading-end detection timing of the document detecting
sensor 15R (S102). In the fourth operational example, what is
conveyed is a regular document sheet that is not held in the
carrier sheet 40. Therefore, the CPU 21 determines that the
document-leading-end detection timing of the document detecting
sensor 15L is coincident with the document-leading-end detection
timing of the document detecting sensor 15R, by a time delay
corresponding to the cutout 41 (S102: Yes). Thereafter, the CPU 21
goes to S110.
[0101] In S110, the CPU 21 determines whether the attenuation
amount based on the amplitude information received from the
multi-feed detector 13 is more than the predetermined threshold
indicating occurrence of multi-feed. In the fourth operational
example, multi-feed is not occurring at this point of time
immediately after the event occurrence timing t33. Therefore, the
CPU 21 determines that the attenuation amount based on the
amplitude information received from the multi-feed detector 13 is
not more than the predetermined threshold indicating occurrence of
multi-feed (S110: No). Thereafter, in response to the negative
determination in S110, the CPU 21 goes to S111.
[0102] At an operation executing timing t34, the CPU 21 transmits
to the reading unit 16 a turn-on instruction to turn on the light
source 51 (S111). In response to receipt of the turn-on
instruction, the reading unit 16 turns on the light source 51. To
read the document sheet in color, the reading unit 16 turns on the
LEDs of the three primary colors RGB in a time division manner. To
read the document sheet in monochrome, the reading unit 16 turns on
one or all of the LEDs of the three primary colors RGB.
[0103] The CPU executes S112, S113, and S114 during a time period
from the operation executing timing t34 to an event occurrence
timing t36. The light receiver 52 receives light reflected by the
document sheet, and transmits to the AFE 50 an analog signal
corresponding to a quantity of the received light. The AFE 50
performs A/D conversion of the received analog signal, and
transmits a digital signal acquired through the A/D conversion to
the CPU 21. Further, the CPU 21 combines a plurality of pieces of
read data, and stores into the RAM 23 the combined data as image
data of a single image (S112).
[0104] An event occurrence timing t35 is a particular point of time
when the amplitude information output from the multi-feed detector
13 changes. At the event occurrence timing t35, the CPU 21
determines whether the attenuation amount based on the amplitude
information received from the multi-feed detector 13 is more than
the threshold indicating occurrence of multi-feed that is
previously stored in the ROM 22 (S113). In the fourth operational
example, drawing multi-feed occurs at this point of time.
Therefore, the CPU 21 determines that the attenuation amount based
on the amplitude information received from the multi-feed detector
13 is more than the threshold indicating occurrence of multi-feed
(S113: Yes). Thereafter, in response to the affirmative
determination in S113, the CPU 21 goes to S140.
[0105] As exemplified in the fourth operational example, there may
be a case where it is determined that multi-feed has occurred in
the middle of document conveyance. In such a case, the multi-feed
is caused when a document sheet to be subsequently read is drawn to
the document sheet being currently conveyed, by a frictional force
or an electrostatic force. The document detecting sensors 15L and
15R are configured to detect existence of a conveyed object and
continue to detect the conveyed object until conveyance of the
conveyed object is completed. Further, the conveyed object has
already been identified as a document sheet. Therefore, there is no
need to determine that the conveyed object is a document sheet,
based on a plurality of pieces of detection information output from
the document detecting sensors 15L and 15R sensors. Thus, in S113,
it is determined whether multi-feed is occurring, based only on the
detection information output from the multi-feed detector 13,
without relying on the detection information output from the
document detector 15.
[0106] In S140, at an operation executing timing t36, the CPU 21
transmits to the reading unit 16 a turn-off instruction to turn off
the light source 51. In response to receipt of the turn-off
instruction, the reading unit 16 turns off the light source 51.
Thereafter, the CPU 21 goes to S130. In S140, when the turn-off
instruction is issued, the document reading is stopped.
Nevertheless, data read before the document reading is stopped may
be or may not be deleted.
[0107] In S130, at an operation executing timing t37, the CPU 21
transmits to the driving unit 53 a conveyance halting instruction
to halt the conveying operation. In accordance with the conveyance
halting instruction, the driving unit 53 halts the rotations of the
pickup roller 11, the feed rollers 14, and the discharge rollers
17. Further, the CPU 21 turns on an LED, for showing an error, of
the LEDs 7 in red. Thereafter, the CPU 21 terminates the process
shown in FIGS. 6A and 6B.
[0108] As described above, according to the image reader 1, it is
determined whether there is a conveyed object, based on the
detection information output from the document detecting sensors
15L and 15R of the document detector 15. When determining that the
detection information output from the document detecting sensors
15L and 15R satisfies the first state, the controller 20 (the CPU
21) determines whether a plurality of conveyed objects are being
conveyed in a mutually-overlapping manner (i.e., whether multi-feed
is occurring), based on the detection information output from the
multi-feed detector 13. When determining that a plurality of
conveyed objects are being conveyed in a mutually-overlapping
manner, the controller 20 halts at least one of a conveying
operation and a reading operation. Meanwhile, when determining that
the detection information output from the document detecting
sensors 15L and 15R satisfies the second state, the controller 20
(the CPU 21) continues the conveying operation and the reading
operation regardless of the detection information output from the
multi-feed detector 13. Namely, the controller 20 automatically
switches between continuing and halting of the conveying operation
and the reading operation, based on the detection information
output from the document detecting sensors 15L and 15R and the
detection information output from the multi-feed detector 13.
Thereby, it is possible to cause the image reader 1 to read a
document sheet held in the carrier sheet 40 having the cutout 41,
with no need for user's troublesome operations for switching the
operational mode.
[0109] Further, at least two of the document detecting sensors 15L
and 15R may be disposed in the conveyance area defined when the two
side guides 10 are positioned closest to each other. Thereby, even
in a conveying operation and a reading operation for a document
sheet that has a width corresponding to the conveyance area defined
when the two side guides 10 are positioned closest to each other,
each of the document detecting sensors 15L and 15R is allowed to
accurately detect existence of the document sheet. Accordingly, it
is possible to more certainly perform a conveying operation and a
reading operation for a document sheet and for a document sheet
held in the carrier sheet 40 having the cutout 41.
[0110] When a plurality of document sheets are stacked on the
document tray 3, an electrostatic force and a frictional force are
applied between a first document sheet to be conveyed by a document
conveyor (e.g., the pickup roller 11, the feed rollers 14, and the
discharge rollers 17) and a second document sheet to be
subsequently conveyed thereby. Therefore, when the two document
sheets are consecutively read, the second document sheet might be
drawn to the first document sheet. In this case, after the
controller 20 once determines that multi-feed is not occurring and
continues the reading operation, the detection information output
from the multi-feed detector 13 shows occurrence of multi-feed.
Nevertheless, each of the document detecting sensors 15L and 15R is
configured to detect existence of a conveyed object, and continue
to detect the conveyed object until conveyance of the conveyed
object is completed. Accordingly, when the controller 20 continues
a control process, the controller 20 is not allowed to determine
whether the detection information output from the document
detecting sensors 15L and 15R satisfies the first state or the
second state. It is noted that the control process is a process of
controlling the conveying operation and the reading operation based
on the detection information output from the multi-feed detector 13
and the detection information output from the document detecting
sensors 15L and 15R. Further, the conveyed object is identified as
a document sheet. Therefore, there is no need to determine whether
the detection information output from the document detecting
sensors 15L and 15R satisfies the first state or the second state.
Thus, after continuing the conveying operation and the reading
operation, the controller 20 determines whether a plurality of
conveyed objects are being conveyed in a mutually-overlapping
manner (i.e., whether multi-feed is occurring) based on the
detection information output from the multi-feed detector 13, until
the controller 20 determines that there is not any conveyed object
based on the detection information output from the document
detecting sensors 15L and 15R. When determining that a plurality of
conveyed objects are being conveyed in a mutually-overlapping
manner, the controller 20 halts at least one of the conveying
operation and the reading operation, regardless of whether the
detection information output from the document detecting sensors
15L and 15R satisfies the first state or the second state. Thereby,
the second document sheet drawn to the first document sheet is not
read.
[0111] Further, when determining that there is a conveyed object
based on the detection information output from the document
detecting sensors 15L and 15R after having once determined that
there is not any conveyed object based on the detection information
output from the document detecting sensors 15L and 15R, the
controller 20 again executes the conveying operation and the
reading operation. Thereby, the controller 20 executes the
conveying operation and the reading operation for each of document
sheets to be successively read. Further, the controller 20 controls
the reading unit 16 to successively read the document sheets, while
identifying for each conveyed object whether a currently conveyed
object is a document sheet or the carrier sheet 40 with a document
sheet held therein.
[0112] Suppose for instance that the carrier sheet 40 has a hole
formed therein (instead of the cutout 41) and that the document
detector 15 detects the hole of the carrier sheet 40. The higher a
conveyance speed of the document conveyor (e.g., the pickup roller
11, the feed rollers 14, and the discharge rollers 17) is, the
shorter a time period is between a point of time when the rotatable
element 15A comes into contact with the hole and a point of time
when the rotatable element 15A completes the contact and begin to
separate from the hole. Hence, the photo-coupler 15B of the
document detector 15 might not detect the rotation of the rotatable
element 15A. In this case, in the control process, the controller
20 might mistakenly determine that a plurality of document sheets,
each of which is not held in the carrier sheets 40, are being
conveyed in a mutually-overlapping manner. Thus, in this case, the
document sheet held in the carrier sheet 40 having the hole might
not be read. In view of the above problem, according to the image
reader 1 of the illustrative embodiment, the carrier sheet 40 has
the cutout 41 formed at the leading end portion 40A that is a
bonded portion of the two transparent sheets. The detection
information output from the document detecting sensors 15L and 15R
includes a detection point of time (detection timing) when the
rotatable element 15A of the document detecting sensor 15L comes
into contact with the cutout 41 of the carrier sheet 40, and a
detection point of time (detection timing) when the rotatable
element 15A of the document detecting sensor 15R comes into contact
with a part of the leading end portion 40A where the cutout 41 is
not formed. The controller 20 performs a predetermined control
process based on the detection points of time. Thereby, it is
possible to more accurately detect the detection timing when the
rotatable element 15A of the document detecting sensor 15L comes
into contact with the cutout 41 of the carrier sheet 40 and the
detection timing when the rotatable element 15A of the document
detecting sensor 15R comes into contact with a part of the leading
end portion 40A where the cutout 41 is not formed. Thus, it is
possible to discriminate the carrier sheet 40 with a document sheet
held therein from a document sheet not held in the carrier sheet
40, and to read the document sheet held in the carrier sheet
40.
[0113] Hereinabove, the illustrative embodiment according to
aspects of the present disclosure has been described. The present
disclosure can be practiced by employing conventional materials,
methodology and equipment. Accordingly, the details of such
materials, equipment and methodology are not set forth herein in
detail. In the previous descriptions, numerous specific details are
set forth, such as specific materials, structures, chemicals,
processes, etc., in order to provide a thorough understanding of
the present disclosure. However, it should be recognized that the
present disclosure can be practiced without reapportioning to the
details specifically set forth. In other instances, well known
processing structures have not been described in detail, in order
not to unnecessarily obscure the present disclosure.
[0114] Only an exemplary illustrative embodiment of the present
disclosure and but a few examples of their versatility are shown
and described in the present disclosure. It is to be understood
that the present disclosure is capable of use in various other
combinations and environments and is capable of changes or
modifications within the scope of the inventive concept as
expressed herein. For instance, according to aspects of the present
disclosure, the following modifications are possible.
[0115] <Modification>
[0116] (1) In the aforementioned illustrative embodiment, aspects
of the present disclosure are applied to the image reader 1.
Nevertheless, aspects of the present disclosure may be applied to
other apparatuses such as a facsimile machine, a copy machine, an
image scanner, and a multi-function peripheral having at least two
of a facsimile function, a copy function, and an image reading
function.
[0117] (2) In the aforementioned illustrative embodiment, the
document separator 12 is a plate-shaped member. Nevertheless, the
document separator 12 may be a reversing roller configured to
rotate in a rotational direction opposite to a rotational direction
of the pickup roller 11. In this case, the document separator 12
may be disposed to face the pickup roller 11 across the conveyance
path 30. The document separator 12 may be configured to separate
document sheets on a sheet-by-sheet basis by action of a frictional
force.
[0118] (3) In the aforementioned illustrative embodiment, the
multi-feed detector 13 is a supersonic sensor. Nevertheless, the
multi-feed detector 13 may be an infrared sensor. In this case, in
the same manner as when the multi-feed detector 13 is a supersonic
sensor, the controller 20 (the CPU 21) may be configured to
determine whether multi-feed is occurring, by determining whether
an attenuation amount, which is determined based on an amplitude of
infrared radiation varying depending on the number of document
sheets, is more than a predetermined threshold indicating
occurrence of multi-feed.
[0119] (4) In the aforementioned illustrative embodiment, the
document detector 15 is disposed at the upper portion 4 of the main
body 2. Nevertheless, the document detector 15 may be disposed at
the lower portion 5 of the main body 2.
[0120] (5) In the aforementioned illustrative embodiment, the
document detector 15 is a contact-type sensor. Nevertheless, the
document detector 15 may be an optical sensor or a magnetic sensor.
Further, instead of the cutout 41, a hole may be formed in the
carrier sheet 40. Suppose, for instance, that the image reader 1
includes an optical sensor as the document detector 15, and that a
hole is formed in the carrier sheet 40, instead of the cutout 41.
In this case, after the optical sensor 15 has detected a leading
end of the carrier sheet 40, the optical sensor 15 is once brought
into a state where the document detecting sensor 15L does not
detect the carrier sheet 40 because of existence of the hole formed
in the carrier sheet 40. Thereafter, the document detecting sensor
15L detects the carrier sheet 40 again. Thus, the controller 20
(the CPU 21) is allowed to determine whether the currently conveyed
object is the carrier sheet 40, based on appearance patterns of the
document-leading-end detection timing and the document-trailing-end
detection timing, in the same manner as exemplified in the
aforementioned illustrative embodiment.
[0121] (6) In the aforementioned illustrative embodiment, if the
leading end portion 40A of the carrier sheet 40 has a hole instead
of the cutout 41, the CPU 21 may determine whether the currently
conveyed object is a document sheet (i.e., the detection
information satisfies the first state) or the carrier sheet 40 with
a document sheet held therein (i.e., the detection information
satisfies the second state), based on an appearance pattern of
document-leading-end detection timings and document-trailing-end
detection timings. Suppose, for instance, that the CPU 21
simultaneously detects a document-leading-end detection timing of
the document detecting sensor 15L and a document-leading-end
detection timing of the document detecting sensor 15R, and
thereafter, the CPU 21 detects a document-trailing-end detection
timing and a document-leading-end detection timing of the document
detecting sensor 15R, in the above order. In this case, the CPU 21
receives, from the document detector 15 (more specifically, from
the document detecting sensor 15R), the detection information
showing such a predetermined detection pattern that the ON
information and the OFF information are switched. When determining
that the currently conveyed object has a hole, based on the
predetermined detection pattern, the CPU 21 makes a negative
determination in S102 (S102: No) of the process shown in FIGS. 6A
and 6B. Meanwhile, when the CPU 21 simultaneously detects a
document-leading-end detection timing of the document detecting
sensor 15L and a document-leading-end detection timing of the
document detecting sensor 15R, and thereafter, the CPU 21 does not
detect the predetermined detection pattern, the CPU 21 determines
that the currently conveyed object does not have a hole. In this
case, the CPU 21 makes an affirmative determination in S102 (S102:
Yes). It is noted that a case where any of the document detecting
sensors 15L and 15R does not detect the predetermined detection
pattern is an example of the first state. Further, a case where one
of the document detecting sensors 15L and 15R detects the
predetermined detection pattern is an example of the second
state.
[0122] Further, in the modification (6), the determination in S102
may be made based on whether there is a time period during which
the detection information output from the document detecting sensor
15L is different from the detection information output from the
document detecting sensor 15R, during a detectable time period from
a point of time when the leading end of the conveyed object has
been detected. It is noted that the detectable time period is a
time period determined based on a conveyance speed of the carrier
sheet 40 in the conveyance direction and a length of the leading
end portion 40A having the hole in the conveyance direction. The
detectable time period may previously be stored in the ROM 22.
[0123] (7) In the aforementioned illustrative embodiment, the
document detecting sensors 15L and 15R are arranged apart from each
other along the left-to-right direction perpendicular to the
conveyance direction. Nevertheless, the document detecting sensors
15L and 15R may be arranged apart from each other along a direction
that is not perpendicular to but intersecting the conveyance
direction. In this case, the determination in S102 as to whether
the document-leading-end detection timing of the document detecting
sensor 15L is coincident with the document-leading-end detection
timing of the document detecting sensor 15R may be made on the
basis of a determination criteria that varies depending on a
positional relationship between the document detecting sensors 15L
and 15R. Suppose, for instance, that a document sheet not held in
the carrier sheet 40 is conveyed, and that a time difference
between the document-leading-end detection timings of the document
detecting sensors 15L and 15R is 0.03 seconds. In this case,
information on the time difference "0.03 seconds" may previously be
stored in the ROM 22. To an earlier one of the document-leading-end
detection timings of the document detecting sensors 15L and 15R,
0.03 seconds may be added. The CPU 21 may determine whether a
timing obtained by adding 0.03 seconds to the earlier one of the
document-leading-end detection timings is coincident with a later
one of the document-leading-end detection timings. When determining
that the timing obtained by adding 0.03 seconds to the earlier one
of the document-leading-end detection timings is coincident with a
later one of the document-leading-end detection timings (S102:
Yes), the CPU 21 may go to S110. Meanwhile, when determining that
the timing obtained by adding 0.03 seconds to the earlier one of
the document-leading-end detection timings is different from the
later one of the document-leading-end detection timings (S102: No),
the CPU 21 may go to S120. It is noted that the case where the
timing obtained by adding 0.03 seconds to the earlier one of the
document-leading-end detection timings is coincident with the later
one of the document-leading-end detection timings is an example of
the first state. Further, the case where the timing obtained by
adding 0.03 seconds to the earlier one of the document-leading-end
detection timings is different from the later one of the
document-leading-end detection timings is an example of the second
state.
[0124] (8) In the aforementioned illustrative embodiment, the
document detecting sensors 15L and 15R are arranged apart from each
other along the left-to-right direction perpendicular to the
conveyance direction. Nevertheless, the document detecting sensors
15L and 15R may be arranged apart from each other along a direction
that is not perpendicular to but intersecting the conveyance
direction. Further, the carrier sheet 40 may have a hole instead of
the cutout 41. In this case, suppose, for instance, that a document
sheet not held in the carrier sheet 40 is conveyed, and that a time
difference between the document-leading-end detection timings of
the document detecting sensors 15L and 15R is 0.03 seconds, as
exemplified in the modification (7). In this case, information on
the time difference "0.03 seconds" may previously be stored in the
ROM 22. To an earlier one of the document-leading-end detection
timings of the document detecting sensors 15L and 15R, 0.03 seconds
may be added.
[0125] Further, when the carrier sheet 40 having a hole is
conveyed, in addition to the above operations, the CPU 21 may
determine whether the currently conveyed object is a document sheet
or the carrier sheet 40 with a document sheet held therein, based
on an appearance pattern of document-leading-end detection timings
and document-trailing-end detection timings, in the same manner as
exemplified in the modification (6). Suppose, for instance, that
the CPU 21 simultaneously detects a document-leading-end detection
timing of the document detecting sensor 15L and a
document-leading-end detection timing of the document detecting
sensor 15R, and thereafter, the CPU 21 detects a
document-trailing-end detection timing and a document-leading-end
detection timing of the document detecting sensor 15R, in the above
order. In this case, the CPU 21 receives, from the document
detector 15 (more specifically, from the document detecting sensor
15R), the detection information showing such a predetermined
detection pattern that the ON information and the OFF information
are switched. When detecting the predetermined detection pattern,
the CPU 21 determines that the currently conveyed object has a
hole, and makes a negative determination in S102 (S102: No).
Meanwhile, when the CPU 21 simultaneously detects a
document-leading-end detection timing of the document detecting
sensor 15L and a document-leading-end detection timing of the
document detecting sensor 15k, and thereafter, the CPU 21 does not
detect the predetermined detection pattern, the CPU 21 determines
that the currently conveyed object does not have a hole. In this
case, the CPU 21 makes an affirmative determination in S102 (S102:
Yes). It is noted that a case where any of the document detecting
sensors 15L and 15R does not detect the predetermined detection
pattern is an example of the first state. Further, a case where one
of the document detecting sensors 15L and 15R detects the
predetermined detection pattern is an example of the second
state.
[0126] (9) In the aforementioned illustrative embodiment and the
modifications (6), (7), and (8), examples of the determination in
S102 have been cited. The examples of the determination in S102 may
be examples of a determination as to whether a detection
information generating state is the first state or the second
state. Further, the affirmative determination in S102 (S102: Yes)
may be an example of a determination that the detection information
generating state is the first state. The negative determination in
S102 (S102: No) may be an example of a determination that the
detection information generating state is the second state. It is
noted that a case where the detection information generating state
is the first state may represent a case where a document sheet not
held in the carrier sheet 40 is conveyed. Meanwhile, a case where
the detection information generating state is the second state may
represent a case where a document sheet held in the carrier sheet
40 is conveyed, and detection information is generated based on the
cutout 41 or the hole of the carrier sheet 40.
[0127] (10) In the aforementioned illustrative embodiment, the
reading operation may include S120 and S121, and S111 and S112 to
be executed by the CPU 21. To "halt the reading operation" may
represent execution of S115, S123, or S140 by the CPU 21. To
"continue the reading operation" may represent that the CPU 21 does
not transmit to the reading unit 16 a turn-off instruction to turn
off the light source 51, or may represent that the CPU 21 transmits
a reading continuing instruction to the reading unit 16. Anyway,
the expression "continue the reading operation" only requires that
document reading is continued. Further, the conveying operation may
include S100 to be executed by the CPU 21. To "halt the conveying
operation" may represent execution of S116, S124, or S130 by the
CPU 21. To "continue the conveying operation" may represent that
the CPU 21 does not transmit a conveyance halting instruction to
the driving unit 53, or may represent that the CPU 21 transmits a
conveyance continuing instruction to the driving unit 53. Anyway,
the expression "continue the conveying operation" only requires
that document conveyance is continued.
[0128] (11) In the aforementioned illustrative embodiment, when
determining that a plurality of document sheets are being conveyed
in a mutually-overlapping manner, the CPU 21 halts the reading
operation in S140 and halts the conveying operation in S130.
However, when determining that a plurality of document sheets are
being conveyed in a mutually-overlapping manner, the CPU 21 may
halt at least one of the reading operation and the conveying
operation. For instance, when the reading operation is halted, and
the conveying operation is continued, the document sheet may be
conveyed downstream in the conveyance direction and discharged out
of the main body 2 by the discharge rollers 17, without being read.
Further, when the reading operation is continued, and the conveying
operation is halted, read data may be stored or deleted.
[0129] (12) As exemplified in the modification (11), when the
reading operation is halted, and the conveying operation is
continued, the document sheet may be conveyed downstream in the
conveyance direction and discharged out of the main body 2 by the
discharge rollers 17, without being read. Nevertheless, when the
reading operation is halted, and the conveying operation is
continued, the document sheet may be conveyed to the document tray
3 in an upstream position in the conveyance direction, by the
driving unit 53 being reversely rotated.
[0130] (13) In the aforementioned illustrative embodiment, the CPU
21 terminates the process shown in FIGS. 6A and 6B after
transmitting the conveyance halting instruction to the driving unit
53 (S130) in response to determining that multi-feed is occurring
(S110: Yes). Nevertheless, the CPU 21 may not terminate the process
shown in FIGS. 6A and 6B after transmitting the conveyance halting
instruction to the driving unit 53 in response to determining that
multi-feed is occurring. In this case, the CPU 21 may resume the
process shown in FIGS. 6A and 6B in accordance with information
input through an operation of the switches 6.
[0131] (14) In the aforementioned illustrative embodiment, the
conveyance area between the two side guides 10 is defined to have a
left section and a right section of the same width in the
left-to-right direction with respect to a center of the conveyance
path 30 in the left-to-right direction. In other words, a left end
and a right end of the conveyance area defined between the two side
guides 10 are positioned the same distance away, in respective
different directions along the left-to-right direction, from the
center of the conveyance path 30 in the left-to-right direction.
Nevertheless, one of the two side guides 10 may be fixedly
positioned, and the conveyance area may be defined on the basis of
the fixedly-positioned side guide 10. In this case, the two
document detecting sensors 15L and 15R may be disposed between a
left end and a right end of the conveyance area defined when the
two side guides 10 are positioned closest to each other on the
basis of the fixedly-positioned side guide 10.
[0132] (15) In the aforementioned illustrative embodiment, between
the left end 34L and the right end 34R of the conveyance area
defined by the two side guides 10 when the two side guides 10 are
positioned closest to each other in their respective movable areas
32, the two document detecting sensors 15L and 15R are arranged
along the left-to-right direction perpendicular to the conveyance
direction. Further, the two document detecting sensors 15L and 15R
are positioned the same distance away, in respective different
directions along the left-to-right direction, from the middle point
of the length of the document tray 3 in the left-to-right
direction. Nevertheless, the document detecting sensors 15L and 15R
may be arranged apart from each other along a direction
intersecting the conveyance direction, in the conveyance area
defined when the two side guides 10 are positioned farthest from
each other in their respective movable areas 32. Further, when
there is not any conveyed object detected by the document detector
15, the CPU 21 may determine that a document sheet not held in the
carrier sheet 40 is being conveyed, i.e., may make an affirmative
determination in S102 (S102: Yes), and may go to S110.
[0133] (16) In the aforementioned illustrative embodiment, the
multi-feed detector 13 is disposed upstream in the conveyance
direction relative to the document detector 15. However, the
document detector 15 may be disposed upstream in the conveyance
direction relative to the multi-feed detector 13. In this case, a
point of time when the CPU 21 is to transmit the turn-on
instruction to the light source 51 in S111 and S120 may be delayed
by a conveyance time period. It is noted that the conveyance time
period may be a time period from a point of time when the document
sheet or the carrier sheet 40 is detected by the document detector
15 to a point of time when the document sheet or the carrier sheet
40 reaches the reading unit 16. Alternatively, when the document
sheet or the carrier sheet 40 is detected by the document detector
15, the CPU 21 may transmit the turn-on instruction to the light
source 51. Then, after the reading operation, the CPU 21 may
delete, from read data in the reading operation, a partial data
section generated when the reading unit 16 was not reading the
document sheet or the document sheet held in the carrier sheet
40.
[0134] (17) In the aforementioned illustrative embodiment, in S110
and S113, the CPU 21 determines whether a plurality of document
sheets are being conveyed in a mutually-overlapping manner (i.e.,
whether multi-feed is occurring) by comparing the attenuation
amount based on the amplitude information received from the
multi-feed detector 13 with the threshold representing occurrence
of multi-feed. Nevertheless, the CPU 21 may determine whether a
plurality of document sheets are being conveyed in a
mutually-overlapping manner by comparing the amplitude information
received from the multi-feed detector 13 with a threshold as an
amplitude value representing occurrence of multi-feed. For example,
the CPU 21 may compare an amplitude value specified by the
amplitude information with the threshold that is the amplitude
value representing occurrence of multi-feed. When determining that
the amplitude value specified by the amplitude information is not
more than the threshold as an amplitude value representing
occurrence of multi-feed, the CPU 21 may determine that multi-feed
is occurring. When determining that the amplitude value specified
by the amplitude information is more than the threshold that is the
amplitude value representing occurrence of multi-feed, the CPU 21
may determine that multi-feed is not occurring.
[0135] (18) In the aforementioned illustrative embodiment, the
document detector 15 includes the two document detecting sensors
15L and 15R. However, the document detector 15 may include three or
more document detecting sensors. For instance, when the document
detector 15 includes three document detecting sensors, two of the
document detecting sensors may detect the leading end portion 40A
of the carrier sheet 40, and the other one document sensor may
detect the cutout 41 of the carrier sheet 40. Thereby, it is
possible to make a discrimination between the carrier sheet 40 and
a document sheet and to automatically switch the operational
mode.
[0136] (19) In the aforementioned illustrative embodiment, the
reading unit 16 includes the CISs. Nevertheless, the reading unit
16 may include charge coupled devices (hereinafter referred to as
"CCDs").
[0137] (20) According to aspects of the present disclosure, the two
side guides 10 are provided, which are configured to move along the
left-to-right direction perpendicular to the conveyance direction.
Nevertheless, the two side guides 10 may be configured to move
along a direction intersecting the conveyance direction at an angle
of 90.+-.0.5 degrees.
Advantageous Effects of Illustrative Embodiment
[0138] The document detecting sensors 15L and 15R are disposed the
same distance away, in respective different directions along the
left-to-right direction, from the middle point of the document tray
3 in the left-to-right direction. Further, the cutout 41 is formed
in a position of the carrier sheet 40 corresponding to one of the
document detecting sensors 15L and 15R. Suppose, for instance, that
two surfaces of the carrier sheet 40 are defined as a first side
and a second side opposite to the first side, respectively. In this
case, the cutout 41 is detected by one of the document detecting
sensors 15L and 15R regardless of whether an upward-facing side of
the carrier sheet 40 being conveyed is the first side or the second
side. Suppose, for instance, that the cutout 41 is formed in a
position of the carrier sheet 40 corresponding to the document
detecting sensor 15R when the carrier sheet 40 is conveyed with the
first side thereof facing upward. In this case, even though the
carrier sheet 40 is conveyed with the first side thereof facing
downward, the cutout 41 is detected by the document detecting
sensor 5L. Thereby, it is possible to read a document sheet held in
the carrier sheet 40.
* * * * *